This invention relates to a light exposure apparatus which is used in manufacturing semiconductor integrated circuits (IC), and more particularly relates to a light exposure apparatus which is used for forming super minute patterns and used for a photolithography process in manufacturing ultra large scale integrated circuits (ULSI).
At present, a light exposure apparatus is generally used in a photolithography process for IC manufacture, and an electron beam exposure apparatus is used for manufacturing photomasks etc. Further, considering the possible advent of devices of further higher density and larger scale integration, a direct writing method is being studied which uses an electron beam and X-ray exposure method.
The electron beam exposure method has some drawbacks that throughput is not so good although it is easy to form minute patterns. The X-ray exposure method obtains not-so-bad throughput by use of SOR-X-ray source etc., but has some drawbacks with the alignment system so that it has not yet been used in practice.
On the other hand, conventional light exposure apparatus obtains a high rate of throughput, but, since it uses g-rays or i-rays of an ultra high pressure mercury lamp and there occurs a decrease of resolution by light diffraction and interference, the pattern forming is limited to approximately 1 .mu.m.
To achieve a more minute pattern, i.e., a pattern of less than 1 .mu.m, the development of a light exposure apparatus has been carried out, which apparatus uses a light of lower wavelength such as an eximer laser [for example, XeCl (308 nm), KrF (248 nm), ArF (193 nm)]. In such case, if such lower wavelength light enables more minute pattern resolution, it necessarily requires an increase in the preciseness of alignment to reduce the distortion of patterns. For example, alignment preciseness of 0.05 .mu.m is required to achieve a pattern of 0.5 .mu.m. However, it is difficult to accomplish this requirement at the present time.